1. Field of the Invention
The present invention relates to a paper fluorescence detection sensor used for judging the type or authenticity of paper such as banknotes and the like.
2. Description of the Related Art
The conventional technology of this technological field is described in Japan Patent Kouhyou No. Hei9-507326(WO95/19019). In the apparatus described in this open publication, a banknote is illuminated with UV radiation, the level of UV light reflected by the banknote is measured by a first photocell, at the same time the intensity of fluorescence generated on the banknote is measured by a second photocell, and the authenticity of the banknote is determined based on both results of measurement by the first and second photocell.
However, the following problems are associated with the above-described conventional apparatus. That is, the intensity of UY radiation illuminating the banknote tends to be unstable at the initial stage when the light source is turned on, and often fluctuates due to voltage fluctuations or degradation over time. As a result, the authenticity of banknotes and the like may not be detected accurately.